usbnet: CDC EEM support (v5)

This introduces a CDC Ethernet Emulation Model (EEM) host side driver to support USB EEM devices. EEM is different from the Ethernet Control Model (ECM) currently supported by the "CDC Ethernet" driver. One key difference is that it doesn't require of USB interface alternate settings to manage interface state; some maldesigned hardware can't handle that part of USB. It also avoids a separate USB interface for control and status updates. [ dbrownell@users.sourceforge.net: fix skb leaks, add rx packet checks, improve fault handling, EEM conformance updates, cleanup ] Signed-off-by: Omar Laazimani <omar.oberthur@gmail.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: David S. Miller <davem@davemloft.net>

usbnet: CDC EEM support (v5)
This introduces a CDC Ethernet Emulation Model (EEM) host side driver to support USB EEM devices. EEM is different from the Ethernet Control Model (ECM) currently supported by the "CDC Ethernet" driver. One key difference is that it doesn't require of USB interface alternate settings to manage interface state; some maldesigned hardware can't handle that part of USB. It also avoids a separate USB interface for control and status updates. [ dbrownell@users.sourceforge.net: fix skb leaks, add rx packet checks, improve fault handling, EEM conformance updates, cleanup ] Signed-off-by: Omar Laazimani <omar.oberthur@gmail.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Omar Laazimani · David S. Miller
1 parent 0c266898b4
Showing 4 changed files with 399 additions and 0 deletions Side-by-side Diff
drivers/net/usb/Kconfig
drivers/net/usb/Makefile
drivers/net/usb/cdc_eem.c
include/linux/usb/cdc.h
@@ -180,6 +180,20 @@
 	  IEEE 802 "local assignment" bit is set in the address, a "usbX"
 	  name is used instead.
  
+config USB_NET_CDC_EEM
+	tristate "CDC EEM support"
+	depends on USB_USBNET && EXPERIMENTAL
+	help
+	  This option supports devices conforming to the Communication Device
+	  Class (CDC) Ethernet Emulation Model, a specification that's easy to
+	  implement in device firmware.  The CDC EEM specifications are available
+	  from <http://www.usb.org/>.
+
+	  This driver creates an interface named "ethX", where X depends on
+	  what other networking devices you have in use.  However, if the
+	  IEEE 802 "local assignment" bit is set in the address, a "usbX"
+	  name is used instead.
+
 config USB_NET_DM9601
 	tristate "Davicom DM9601 based USB 1.1 10/100 ethernet devices"
 	depends on USB_USBNET
@@ -9,6 +9,7 @@
 obj-$(CONFIG_USB_HSO)		+= hso.o
 obj-$(CONFIG_USB_NET_AX8817X)	+= asix.o
 obj-$(CONFIG_USB_NET_CDCETHER)	+= cdc_ether.o
+obj-$(CONFIG_USB_NET_CDC_EEM)	+= cdc_eem.o
 obj-$(CONFIG_USB_NET_DM9601)	+= dm9601.o
 obj-$(CONFIG_USB_NET_SMSC95XX)	+= smsc95xx.o
 obj-$(CONFIG_USB_NET_GL620A)	+= gl620a.o
+/*
+ * USB CDC EEM network interface driver
+ * Copyright (C) 2009 Oberthur Technologies
+ * by Omar Laazimani, Olivier Condemine
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ctype.h>
+#include <linux/ethtool.h>
+#include <linux/workqueue.h>
+#include <linux/mii.h>
+#include <linux/usb.h>
+#include <linux/crc32.h>
+#include <linux/usb/cdc.h>
+#include <linux/usb/usbnet.h>
+
+
+/*
+ * This driver is an implementation of the CDC "Ethernet Emulation
+ * Model" (EEM) specification, which encapsulates Ethernet frames
+ * for transport over USB using a simpler USB device model than the
+ * previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").
+ *
+ * For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
+ *
+ * This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,
+ * 2.6.27 and 2.6.30rc2 kernel.
+ * It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).
+ * build on 23-April-2009
+ */
+
+#define EEM_HEAD	2		/* 2 byte header */
+
+/*-------------------------------------------------------------------------*/
+
+static void eem_linkcmd_complete(struct urb *urb)
+{
+	dev_kfree_skb(urb->context);
+	usb_free_urb(urb);
+}
+
+static void eem_linkcmd(struct usbnet *dev, struct sk_buff *skb)
+{
+	struct urb		*urb;
+	int			status;
+
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb)
+		goto fail;
+
+	usb_fill_bulk_urb(urb, dev->udev, dev->out,
+			skb->data, skb->len, eem_linkcmd_complete, skb);
+
+	status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (status) {
+		usb_free_urb(urb);
+fail:
+		dev_kfree_skb(skb);
+		devwarn(dev, "link cmd failure\n");
+		return;
+	}
+}
+
+static int eem_bind(struct usbnet *dev, struct usb_interface *intf)
+{
+	int status = 0;
+
+	status = usbnet_get_endpoints(dev, intf);
+	if (status < 0) {
+		usb_set_intfdata(intf, NULL);
+		usb_driver_release_interface(driver_of(intf), intf);
+		return status;
+	}
+
+	/* no jumbogram (16K) support for now */
+
+	dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN;
+
+	return 0;
+}
+
+/*
+ * EEM permits packing multiple Ethernet frames into USB transfers
+ * (a "bundle"), but for TX we don't try to do that.
+ */
+static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
+				       gfp_t flags)
+{
+	struct sk_buff	*skb2 = NULL;
+	u16		len = skb->len;
+	u32		crc = 0;
+	int		padlen = 0;
+
+	/* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
+	 * zero, stick two bytes of zero length EEM packet on the end.
+	 * Else the framework would add invalid single byte padding,
+	 * since it can't know whether ZLPs will be handled right by
+	 * all the relevant hardware and software.
+	 */
+	if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
+		padlen += 2;
+
+	if (!skb_cloned(skb)) {
+		int	headroom = skb_headroom(skb);
+		int	tailroom = skb_tailroom(skb);
+
+		if ((tailroom >= ETH_FCS_LEN + padlen)
+				&& (headroom >= EEM_HEAD))
+			goto done;
+
+		if ((headroom + tailroom)
+				> (EEM_HEAD + ETH_FCS_LEN + padlen)) {
+			skb->data = memmove(skb->head +
+					EEM_HEAD,
+					skb->data,
+					skb->len);
+			skb_set_tail_pointer(skb, len);
+			goto done;
+		}
+	}
+
+	skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
+	if (!skb2)
+		return NULL;
+
+	dev_kfree_skb_any(skb);
+	skb = skb2;
+
+done:
+	/* we don't use the "no Ethernet CRC" option */
+	crc = crc32_le(~0, skb->data, skb->len);
+	crc = ~crc;
+
+	put_unaligned_le32(crc, skb_put(skb, 4));
+
+	/* EEM packet header format:
+	 * b0..13:	length of ethernet frame
+	 * b14:		bmCRC (1 == valid Ethernet CRC)
+	 * b15:		bmType (0 == data)
+	 */
+	len = skb->len;
+	put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
+
+	/* Bundle a zero length EEM packet if needed */
+	if (padlen)
+		put_unaligned_le16(0, skb_put(skb, 2));
+
+	return skb;
+}
+
+static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+{
+	/*
+	 * Our task here is to strip off framing, leaving skb with one
+	 * data frame for the usbnet framework code to process.  But we
+	 * may have received multiple EEM payloads, or command payloads.
+	 * So we must process _everything_ as if it's a header, except
+	 * maybe the last data payload
+	 *
+	 * REVISIT the framework needs updating so that when we consume
+	 * all payloads (the last or only message was a command, or a
+	 * zero length EEM packet) that is not accounted as an rx_error.
+	 */
+	do {
+		struct sk_buff	*skb2 = NULL;
+		u16		header;
+		u16		len = 0;
+
+		/* incomplete EEM header? */
+		if (skb->len < EEM_HEAD)
+			return 0;
+
+		/*
+		 * EEM packet header format:
+		 * b0..14:	EEM type dependant (Data or Command)
+		 * b15:		bmType
+		 */
+		header = get_unaligned_le16(skb->data);
+		skb_pull(skb, EEM_HEAD);
+
+		/*
+		 * The bmType bit helps to denote when EEM
+		 * packet is data or command :
+		 *	bmType = 0	: EEM data payload
+		 *	bmType = 1	: EEM (link) command
+		 */
+		if (header & BIT(15)) {
+			u16	bmEEMCmd;
+
+			/*
+			 * EEM (link) command packet:
+			 * b0..10:	bmEEMCmdParam
+			 * b11..13:	bmEEMCmd
+			 * b14:		bmReserved (must be 0)
+			 * b15:		1 (EEM command)
+			 */
+			if (header & BIT(14)) {
+				devdbg(dev, "reserved command %04x\n", header);
+				continue;
+			}
+
+			bmEEMCmd = (header >> 11) & 0x7;
+			switch (bmEEMCmd) {
+
+			/* Responding to echo requests is mandatory. */
+			case 0:		/* Echo command */
+				len = header & 0x7FF;
+
+				/* bogus command? */
+				if (skb->len < len)
+					return 0;
+
+				skb2 = skb_clone(skb, GFP_ATOMIC);
+				if (unlikely(!skb2))
+					goto next;
+				skb_trim(skb2, len);
+				put_unaligned_le16(BIT(15) | (1 << 11) | len,
+						skb_push(skb2, 2));
+				eem_linkcmd(dev, skb2);
+				break;
+
+			/*
+			 * Host may choose to ignore hints.
+			 *  - suspend: peripheral ready to suspend
+			 *  - response: suggest N millisec polling
+			 *  - response complete: suggest N sec polling
+			 */
+			case 2:		/* Suspend hint */
+			case 3:		/* Response hint */
+			case 4:		/* Response complete hint */
+				continue;
+
+			/*
+			 * Hosts should never receive host-to-peripheral
+			 * or reserved command codes; or responses to an
+			 * echo command we didn't send.
+			 */
+			case 1:		/* Echo response */
+			case 5:		/* Tickle */
+			default:	/* reserved */
+				devwarn(dev, "unexpected link command %d\n",
+						bmEEMCmd);
+				continue;
+			}
+
+		} else {
+			u32	crc, crc2;
+			int	is_last;
+
+			/* zero length EEM packet? */
+			if (header == 0)
+				continue;
+
+			/*
+			 * EEM data packet header :
+			 * b0..13:	length of ethernet frame
+			 * b14:		bmCRC
+			 * b15:		0 (EEM data)
+			 */
+			len = header & 0x3FFF;
+
+			/* bogus EEM payload? */
+			if (skb->len < len)
+				return 0;
+
+			/* bogus ethernet frame? */
+			if (len < (ETH_HLEN + ETH_FCS_LEN))
+				goto next;
+
+			/*
+			 * Treat the last payload differently: framework
+			 * code expects our "fixup" to have stripped off
+			 * headers, so "skb" is a data packet (or error).
+			 * Else if it's not the last payload, keep "skb"
+			 * for further processing.
+			 */
+			is_last = (len == skb->len);
+			if (is_last)
+				skb2 = skb;
+			else {
+				skb2 = skb_clone(skb, GFP_ATOMIC);
+				if (unlikely(!skb2))
+					return 0;
+			}
+
+			crc = get_unaligned_le32(skb2->data
+					+ len - ETH_FCS_LEN);
+			skb_trim(skb2, len - ETH_FCS_LEN);
+
+			/*
+			 * The bmCRC helps to denote when the CRC field in
+			 * the Ethernet frame contains a calculated CRC:
+			 *	bmCRC = 1	: CRC is calculated
+			 *	bmCRC = 0	: CRC = 0xDEADBEEF
+			 */
+			if (header & BIT(14))
+				crc2 = ~crc32_le(~0, skb2->data, len);
+			else
+				crc2 = 0xdeadbeef;
+
+			if (is_last)
+				return crc == crc2;
+
+			if (unlikely(crc != crc2)) {
+				dev->stats.rx_errors++;
+				dev_kfree_skb_any(skb2);
+			} else
+				usbnet_skb_return(dev, skb2);
+		}
+
+next:
+		skb_pull(skb, len);
+	} while (skb->len);
+
+	return 1;
+}
+
+static const struct driver_info eem_info = {
+	.description =	"CDC EEM Device",
+	.flags =	FLAG_ETHER,
+	.bind =		eem_bind,
+	.rx_fixup =	eem_rx_fixup,
+	.tx_fixup =	eem_tx_fixup,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static const struct usb_device_id products[] = {
+{
+	USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
+			USB_CDC_PROTO_EEM),
+	.driver_info = (unsigned long) &eem_info,
+},
+{
+	/* EMPTY == end of list */
+},
+};
+MODULE_DEVICE_TABLE(usb, products);
+
+static struct usb_driver eem_driver = {
+	.name =		"cdc_eem",
+	.id_table =	products,
+	.probe =	usbnet_probe,
+	.disconnect =	usbnet_disconnect,
+	.suspend =	usbnet_suspend,
+	.resume =	usbnet_resume,
+};
+
+
+static int __init eem_init(void)
+{
+	return usb_register(&eem_driver);
+}
+module_init(eem_init);
+
+static void __exit eem_exit(void)
+{
+	usb_deregister(&eem_driver);
+}
+module_exit(eem_exit);
+
+MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
+MODULE_DESCRIPTION("USB CDC EEM");
+MODULE_LICENSE("GPL");
@@ -17,6 +17,7 @@
 #define USB_CDC_SUBCLASS_DMM			0x09
 #define USB_CDC_SUBCLASS_MDLM			0x0a
 #define USB_CDC_SUBCLASS_OBEX			0x0b
+#define USB_CDC_SUBCLASS_EEM			0x0c
  
 #define USB_CDC_PROTO_NONE			0
  
@@ -27,6 +28,8 @@
 #define USB_CDC_ACM_PROTO_AT_3G			5
 #define USB_CDC_ACM_PROTO_AT_CDMA		6
 #define USB_CDC_ACM_PROTO_VENDOR		0xff
+
+#define USB_CDC_PROTO_EEM			7
  
 /*-------------------------------------------------------------------------*/
...	...	@@ -180,6 +180,20 @@
180	180	IEEE 802 "local assignment" bit is set in the address, a "usbX"
181	181	name is used instead.
182	182
	183	+config USB_NET_CDC_EEM
	184	+ tristate "CDC EEM support"
	185	+ depends on USB_USBNET && EXPERIMENTAL
	186	+ help
	187	+ This option supports devices conforming to the Communication Device
	188	+ Class (CDC) Ethernet Emulation Model, a specification that's easy to
	189	+ implement in device firmware. The CDC EEM specifications are available
	190	+ from <http://www.usb.org/>.
	191	+
	192	+ This driver creates an interface named "ethX", where X depends on
	193	+ what other networking devices you have in use. However, if the
	194	+ IEEE 802 "local assignment" bit is set in the address, a "usbX"
	195	+ name is used instead.
	196	+
183	197	config USB_NET_DM9601
184	198	tristate "Davicom DM9601 based USB 1.1 10/100 ethernet devices"
185	199	depends on USB_USBNET
...	...	@@ -9,6 +9,7 @@
9	9	obj-$(CONFIG_USB_HSO) += hso.o
10	10	obj-$(CONFIG_USB_NET_AX8817X) += asix.o
11	11	obj-$(CONFIG_USB_NET_CDCETHER) += cdc_ether.o
	12	+obj-$(CONFIG_USB_NET_CDC_EEM) += cdc_eem.o
12	13	obj-$(CONFIG_USB_NET_DM9601) += dm9601.o
13	14	obj-$(CONFIG_USB_NET_SMSC95XX) += smsc95xx.o
14	15	obj-$(CONFIG_USB_NET_GL620A) += gl620a.o
	1	+/*
	2	+ * USB CDC EEM network interface driver
	3	+ * Copyright (C) 2009 Oberthur Technologies
	4	+ * by Omar Laazimani, Olivier Condemine
	5	+ *
	6	+ * This program is free software; you can redistribute it and/or modify
	7	+ * it under the terms of the GNU General Public License as published by
	8	+ * the Free Software Foundation; either version 2 of the License, or
	9	+ * (at your option) any later version.
	10	+ *
	11	+ * This program is distributed in the hope that it will be useful,
	12	+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	+ * GNU General Public License for more details.
	15	+ *
	16	+ * You should have received a copy of the GNU General Public License
	17	+ * along with this program; if not, write to the Free Software
	18	+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	19	+ */
	20	+
	21	+#include <linux/module.h>
	22	+#include <linux/init.h>
	23	+#include <linux/netdevice.h>
	24	+#include <linux/etherdevice.h>
	25	+#include <linux/ctype.h>
	26	+#include <linux/ethtool.h>
	27	+#include <linux/workqueue.h>
	28	+#include <linux/mii.h>
	29	+#include <linux/usb.h>
	30	+#include <linux/crc32.h>
	31	+#include <linux/usb/cdc.h>
	32	+#include <linux/usb/usbnet.h>
	33	+
	34	+
	35	+/*
	36	+ * This driver is an implementation of the CDC "Ethernet Emulation
	37	+ * Model" (EEM) specification, which encapsulates Ethernet frames
	38	+ * for transport over USB using a simpler USB device model than the
	39	+ * previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").
	40	+ *
	41	+ * For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
	42	+ *
	43	+ * This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,
	44	+ * 2.6.27 and 2.6.30rc2 kernel.
	45	+ * It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).
	46	+ * build on 23-April-2009
	47	+ */
	48	+
	49	+#define EEM_HEAD 2 /* 2 byte header */
	50	+
	51	+/-------------------------------------------------------------------------/
	52	+
	53	+static void eem_linkcmd_complete(struct urb *urb)
	54	+{
	55	+ dev_kfree_skb(urb->context);
	56	+ usb_free_urb(urb);
	57	+}
	58	+
	59	+static void eem_linkcmd(struct usbnet dev, struct sk_buff skb)
	60	+{
	61	+ struct urb *urb;
	62	+ int status;
	63	+
	64	+ urb = usb_alloc_urb(0, GFP_ATOMIC);
	65	+ if (!urb)
	66	+ goto fail;
	67	+
	68	+ usb_fill_bulk_urb(urb, dev->udev, dev->out,
	69	+ skb->data, skb->len, eem_linkcmd_complete, skb);
	70	+
	71	+ status = usb_submit_urb(urb, GFP_ATOMIC);
	72	+ if (status) {
	73	+ usb_free_urb(urb);
	74	+fail:
	75	+ dev_kfree_skb(skb);
	76	+ devwarn(dev, "link cmd failure\n");
	77	+ return;
	78	+ }
	79	+}
	80	+
	81	+static int eem_bind(struct usbnet dev, struct usb_interface intf)
	82	+{
	83	+ int status = 0;
	84	+
	85	+ status = usbnet_get_endpoints(dev, intf);
	86	+ if (status < 0) {
	87	+ usb_set_intfdata(intf, NULL);
	88	+ usb_driver_release_interface(driver_of(intf), intf);
	89	+ return status;
	90	+ }
	91	+
	92	+ /* no jumbogram (16K) support for now */
	93	+
	94	+ dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN;
	95	+
	96	+ return 0;
	97	+}
	98	+
	99	+/*
	100	+ * EEM permits packing multiple Ethernet frames into USB transfers
	101	+ * (a "bundle"), but for TX we don't try to do that.
	102	+ */
	103	+static struct sk_buff eem_tx_fixup(struct usbnet dev, struct sk_buff *skb,
	104	+ gfp_t flags)
	105	+{
	106	+ struct sk_buff *skb2 = NULL;
	107	+ u16 len = skb->len;
	108	+ u32 crc = 0;
	109	+ int padlen = 0;
	110	+
	111	+ /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
	112	+ * zero, stick two bytes of zero length EEM packet on the end.
	113	+ * Else the framework would add invalid single byte padding,
	114	+ * since it can't know whether ZLPs will be handled right by
	115	+ * all the relevant hardware and software.
	116	+ */
	117	+ if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
	118	+ padlen += 2;
	119	+
	120	+ if (!skb_cloned(skb)) {
	121	+ int headroom = skb_headroom(skb);
	122	+ int tailroom = skb_tailroom(skb);
	123	+
	124	+ if ((tailroom >= ETH_FCS_LEN + padlen)
	125	+ && (headroom >= EEM_HEAD))
	126	+ goto done;
	127	+
	128	+ if ((headroom + tailroom)
	129	+ > (EEM_HEAD + ETH_FCS_LEN + padlen)) {
	130	+ skb->data = memmove(skb->head +
	131	+ EEM_HEAD,
	132	+ skb->data,
	133	+ skb->len);
	134	+ skb_set_tail_pointer(skb, len);
	135	+ goto done;
	136	+ }
	137	+ }
	138	+
	139	+ skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
	140	+ if (!skb2)
	141	+ return NULL;
	142	+
	143	+ dev_kfree_skb_any(skb);
	144	+ skb = skb2;
	145	+
	146	+done:
	147	+ /* we don't use the "no Ethernet CRC" option */
	148	+ crc = crc32_le(~0, skb->data, skb->len);
	149	+ crc = ~crc;
	150	+
	151	+ put_unaligned_le32(crc, skb_put(skb, 4));
	152	+
	153	+ /* EEM packet header format:
	154	+ * b0..13: length of ethernet frame
	155	+ * b14: bmCRC (1 == valid Ethernet CRC)
	156	+ * b15: bmType (0 == data)
	157	+ */
	158	+ len = skb->len;
	159	+ put_unaligned_le16(BIT(14) \| len, skb_push(skb, 2));
	160	+
	161	+ /* Bundle a zero length EEM packet if needed */
	162	+ if (padlen)
	163	+ put_unaligned_le16(0, skb_put(skb, 2));
	164	+
	165	+ return skb;
	166	+}
	167	+
	168	+static int eem_rx_fixup(struct usbnet dev, struct sk_buff skb)
	169	+{
	170	+ /*
	171	+ * Our task here is to strip off framing, leaving skb with one
	172	+ * data frame for the usbnet framework code to process. But we
	173	+ * may have received multiple EEM payloads, or command payloads.
	174	+ * So we must process _everything_ as if it's a header, except
	175	+ * maybe the last data payload
	176	+ *
	177	+ * REVISIT the framework needs updating so that when we consume
	178	+ * all payloads (the last or only message was a command, or a
	179	+ * zero length EEM packet) that is not accounted as an rx_error.
	180	+ */
	181	+ do {
	182	+ struct sk_buff *skb2 = NULL;
	183	+ u16 header;
	184	+ u16 len = 0;
	185	+
	186	+ /* incomplete EEM header? */
	187	+ if (skb->len < EEM_HEAD)
	188	+ return 0;
	189	+
	190	+ /*
	191	+ * EEM packet header format:
	192	+ * b0..14: EEM type dependant (Data or Command)
	193	+ * b15: bmType
	194	+ */
	195	+ header = get_unaligned_le16(skb->data);
	196	+ skb_pull(skb, EEM_HEAD);
	197	+
	198	+ /*
	199	+ * The bmType bit helps to denote when EEM
	200	+ * packet is data or command :
	201	+ * bmType = 0 : EEM data payload
	202	+ * bmType = 1 : EEM (link) command
	203	+ */
	204	+ if (header & BIT(15)) {
	205	+ u16 bmEEMCmd;
	206	+
	207	+ /*
	208	+ * EEM (link) command packet:
	209	+ * b0..10: bmEEMCmdParam
	210	+ * b11..13: bmEEMCmd
	211	+ * b14: bmReserved (must be 0)
	212	+ * b15: 1 (EEM command)
	213	+ */
	214	+ if (header & BIT(14)) {
	215	+ devdbg(dev, "reserved command %04x\n", header);
	216	+ continue;
	217	+ }
	218	+
	219	+ bmEEMCmd = (header >> 11) & 0x7;
	220	+ switch (bmEEMCmd) {
	221	+
	222	+ /* Responding to echo requests is mandatory. */
	223	+ case 0: /* Echo command */
	224	+ len = header & 0x7FF;
	225	+
	226	+ /* bogus command? */
	227	+ if (skb->len < len)
	228	+ return 0;
	229	+
	230	+ skb2 = skb_clone(skb, GFP_ATOMIC);
	231	+ if (unlikely(!skb2))
	232	+ goto next;
	233	+ skb_trim(skb2, len);
	234	+ put_unaligned_le16(BIT(15) \| (1 << 11) \| len,
	235	+ skb_push(skb2, 2));
	236	+ eem_linkcmd(dev, skb2);
	237	+ break;
	238	+
	239	+ /*
	240	+ * Host may choose to ignore hints.
	241	+ * - suspend: peripheral ready to suspend
	242	+ * - response: suggest N millisec polling
	243	+ * - response complete: suggest N sec polling
	244	+ */
	245	+ case 2: /* Suspend hint */
	246	+ case 3: /* Response hint */
	247	+ case 4: /* Response complete hint */
	248	+ continue;
	249	+
	250	+ /*
	251	+ * Hosts should never receive host-to-peripheral
	252	+ * or reserved command codes; or responses to an
	253	+ * echo command we didn't send.
	254	+ */
	255	+ case 1: /* Echo response */
	256	+ case 5: /* Tickle */
	257	+ default: /* reserved */
	258	+ devwarn(dev, "unexpected link command %d\n",
	259	+ bmEEMCmd);
	260	+ continue;
	261	+ }
	262	+
	263	+ } else {
	264	+ u32 crc, crc2;
	265	+ int is_last;
	266	+
	267	+ /* zero length EEM packet? */
	268	+ if (header == 0)
	269	+ continue;
	270	+
	271	+ /*
	272	+ * EEM data packet header :
	273	+ * b0..13: length of ethernet frame
	274	+ * b14: bmCRC
	275	+ * b15: 0 (EEM data)
	276	+ */
	277	+ len = header & 0x3FFF;
	278	+
	279	+ /* bogus EEM payload? */
	280	+ if (skb->len < len)
	281	+ return 0;
	282	+
	283	+ /* bogus ethernet frame? */
	284	+ if (len < (ETH_HLEN + ETH_FCS_LEN))
	285	+ goto next;
	286	+
	287	+ /*
	288	+ * Treat the last payload differently: framework
	289	+ * code expects our "fixup" to have stripped off
	290	+ * headers, so "skb" is a data packet (or error).
	291	+ * Else if it's not the last payload, keep "skb"
	292	+ * for further processing.
	293	+ */
	294	+ is_last = (len == skb->len);
	295	+ if (is_last)
	296	+ skb2 = skb;
	297	+ else {
	298	+ skb2 = skb_clone(skb, GFP_ATOMIC);
	299	+ if (unlikely(!skb2))
	300	+ return 0;
	301	+ }
	302	+
	303	+ crc = get_unaligned_le32(skb2->data
	304	+ + len - ETH_FCS_LEN);
	305	+ skb_trim(skb2, len - ETH_FCS_LEN);
	306	+
	307	+ /*
	308	+ * The bmCRC helps to denote when the CRC field in
	309	+ * the Ethernet frame contains a calculated CRC:
	310	+ * bmCRC = 1 : CRC is calculated
	311	+ * bmCRC = 0 : CRC = 0xDEADBEEF
	312	+ */
	313	+ if (header & BIT(14))
	314	+ crc2 = ~crc32_le(~0, skb2->data, len);
	315	+ else
	316	+ crc2 = 0xdeadbeef;
	317	+
	318	+ if (is_last)
	319	+ return crc == crc2;
	320	+
	321	+ if (unlikely(crc != crc2)) {
	322	+ dev->stats.rx_errors++;
	323	+ dev_kfree_skb_any(skb2);
	324	+ } else
	325	+ usbnet_skb_return(dev, skb2);
	326	+ }
	327	+
	328	+next:
	329	+ skb_pull(skb, len);
	330	+ } while (skb->len);
	331	+
	332	+ return 1;
	333	+}
	334	+
	335	+static const struct driver_info eem_info = {
	336	+ .description = "CDC EEM Device",
	337	+ .flags = FLAG_ETHER,
	338	+ .bind = eem_bind,
	339	+ .rx_fixup = eem_rx_fixup,
	340	+ .tx_fixup = eem_tx_fixup,
	341	+};
	342	+
	343	+/-------------------------------------------------------------------------/
	344	+
	345	+static const struct usb_device_id products[] = {
	346	+{
	347	+ USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
	348	+ USB_CDC_PROTO_EEM),
	349	+ .driver_info = (unsigned long) &eem_info,
	350	+},
	351	+{
	352	+ /* EMPTY == end of list */
	353	+},
	354	+};
	355	+MODULE_DEVICE_TABLE(usb, products);
	356	+
	357	+static struct usb_driver eem_driver = {
	358	+ .name = "cdc_eem",
	359	+ .id_table = products,
	360	+ .probe = usbnet_probe,
	361	+ .disconnect = usbnet_disconnect,
	362	+ .suspend = usbnet_suspend,
	363	+ .resume = usbnet_resume,
	364	+};
	365	+
	366	+
	367	+static int __init eem_init(void)
	368	+{
	369	+ return usb_register(&eem_driver);
	370	+}
	371	+module_init(eem_init);
	372	+
	373	+static void __exit eem_exit(void)
	374	+{
	375	+ usb_deregister(&eem_driver);
	376	+}
	377	+module_exit(eem_exit);
	378	+
	379	+MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
	380	+MODULE_DESCRIPTION("USB CDC EEM");
	381	+MODULE_LICENSE("GPL");
...	...	@@ -17,6 +17,7 @@
17	17	#define USB_CDC_SUBCLASS_DMM 0x09
18	18	#define USB_CDC_SUBCLASS_MDLM 0x0a
19	19	#define USB_CDC_SUBCLASS_OBEX 0x0b
	20	+#define USB_CDC_SUBCLASS_EEM 0x0c
20	21
21	22	#define USB_CDC_PROTO_NONE 0
22	23
...	...	@@ -27,6 +28,8 @@
27	28	#define USB_CDC_ACM_PROTO_AT_3G 5
28	29	#define USB_CDC_ACM_PROTO_AT_CDMA 6
29	30	#define USB_CDC_ACM_PROTO_VENDOR 0xff
	31	+
	32	+#define USB_CDC_PROTO_EEM 7
30	33
31	34	/-------------------------------------------------------------------------/
32	35